1. Field of the Invention
The present invention relates to a pneumatic tire including a reinforcement layer including reinforcement cords and a method of manufacturing the pneumatic tire. More specifically, the present invention relates to a pneumatic tire with an improved durability which is realized by preventing oxygen deterioration of coating rubber of a reinforcement layer, and to a method of manufacturing the pneumatic tire.
2. Description of the Related Art
Generally speaking, a pneumatic tire includes a reinforcement layer, such as a carcass layer or a belt layer, which is made by covering multiple aligned reinforcement cords with coating rubber. The coating rubber of the reinforcement layer tends to deteriorate due to oxygen included in the air permeating the tire. Deterioration of the coating rubber of the reinforcement layer decreases the durability of the tire.
Recently, a proposal has been made in which a thin film is arranged on the inner surface of the tire as an air permeation preventive layer. The thin film is made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer in a thermoplastic resin (see Japanese patent application Kokai publication Nos. Hei. 8-217923 and Hei. 11-199713, for example). The air permeation preventive layer of this type is advantageous for suppressing deterioration of the coating rubber of a reinforcement layer covered with the air permeation preventive layers because the air permeability of the air permeation preventive layer is low.
The deterioration of the coating rubber of the reinforcement layer progresses not only due to oxygen included in the air filled in the tire, but also due to oxygen included in the atmosphere outside the tire. Particularly in a case where the tire is stored with no internal pressure filled therein, the coating rubber of the reinforcement layer deteriorates due to oxygen included in the air entering the inside of the tire from the outer surface thereof. For this reason, there is a demand to prevent the decrease in the tire durability attributed to the oxygen deterioration of the coating rubber of the reinforcement layer.